This invention relates to electrical signal measurement, and more particularly to vector voltmeters.
The present invention can measure the complex voltage ratio of two sinusoidal signals having the same frequency in any part of the electromagnetic spectrum in which single-mode guided wave propagation is feasible. It is similar to existing vector voltmeters in that it measures the amplitude of both signals and the phase angle between them. However, it differs from prior vector voltmeters and most other phase measuring instruments in that the phase angle is obtained from four simple amplitude detectors rather than from more complicated schemes such as heterodyning the signal down to a lower frequency where the phase angle is measured directly using zero-crossing or other techniques. The six-port approach eliminates timing problems associated with zero-crossing techniques, and simplifies the measurement by not using heterodyne techniques (which usually require two separate sources).